E Ireland wrote:... You are going to have huge problems sourcing anywhere near the amount of fissiles required to start one of these reactors without adopting something that is essentially a DMSR. Breeders always get killed by the doubling time.

That's BS - any of the last four start up scenarios described in my paper would solve that problem within a century or two. It would be the best way to use up the Redbook's current best guess of "affordable uranium" and the uranium mining & separation industries' shareholders would get even richer doing it.

Improving the reference MSFR's CR by surrounding its entire core with blanket salt would make that job quicker/easier. Why don't you think about how that might be accomplished?

darryl siemer wrote:
That's BS - any of the last four start up scenarios described in my paper would solve that problem within a century or two.

A century or two is too long, we will be screwed long before that if we don't go all in for nuclear very soon. You are thinking on far too long a timescale for the current geopolitical and social framework.
We have sufficient uranium to power the world for a dozen centuries or more without much trouble even using DMSRs - expending value resources on breeders at this time does not make any sense, especially if we really can build breeders to completion in a couple of hundred years - why start now? why not start after the low hanging fruit that is uranium converters is gone?.

darryl siemer wrote:
Improving the reference MSFR's CR by surrounding its entire core with blanket salt would make that job quicker/easier. Why don't you think about how that might be accomplished?

Even a doubling time of 20 years is probably too long starting from our current fissile situation (we essentially have nothing but LEU and tiny amounts of reactor grade plutonium, and we will never be allowed bomb grade fissile in large quantities). You will also never be able to get your hands on large quantities of defence plutonium - it is ridiculously expensive to produce and not expensive to store by comparison, only insanity would lead to it being burned away, its a hedge against future needs.

EDIT:
Your paper seems to propose a DMSR that is forced to produce a >1 breeding ratio - even though running a breeding reactor full of 238U is going to be fun and will likely require lots of online processing to hold the breeding ratio at reasonably high values - 1.05 is not going to cut it your mission is to produce lots of fissiles for more startups rapidly.

E Ireland wrote:
Your paper seems to propose a DMSR that is forced to produce a >1 breeding ratio - even though running a breeding reactor full of 238U is going to be fun and will likely require lots of online processing to hold the breeding ratio at reasonably high values - 1.05 is not going to cut it your mission is to produce lots of fissiles for more startups rapidly.

Did you actually read my paper? Its DMSR straw man (footnote 27) is based upon Engle's conception; i.e., exhibits a CR of about 0.8 & is fueled with combination of added 235U, 239Pu in situ bred from 238U & 233U in situ bred from 232Th. I doubt that any sort of DMSR would be capable of achieving breakeven fissile regeneration (CR = 1.00).

E Ireland wrote:
Your paper seems to propose a DMSR that is forced to produce a >1 breeding ratio - even though running a breeding reactor full of 238U is going to be fun and will likely require lots of online processing to hold the breeding ratio at reasonably high values - 1.05 is not going to cut it your mission is to produce lots of fissiles for more startups rapidly.

Did you actually read my paper? Its DMSR straw man (footnote 27) is based upon Engle's conception; i.e., exhibits a CR of about 0.8 & is fueled with combination of added 235U, 239Pu in situ bred from 238U & 233U in situ bred from 232Th. I doubt that any sort of DMSR would be capable of achieving breakeven fissile regeneration (CR = 1.00).

Then how do you intend to use such a reactor to produce suitable startup fissile for a MSBR later on? (You propose using 20% LEU to start breeders, when this causes all sorts of issues as has been discussed more widely by a variety of people). Without bomb grade material enrichment is virtually useless for this purpose.

Unless you are proposing a two fluid reactor an LEU started reactor is unable to produce fissiles useful for starting other breeder type reactors (the enrichment level of the final core is lower than that of the feed due to the conversion ratio being <1).
Having a two fluid reactor introduces all sorts of other horrible problems which explain why such developments were abandoned in favour of single fluid designs.

E Ireland wrote:
...Unless you are proposing a two fluid reactor an LEU started reactor is unable to produce fissiles useful for starting other breeder type reactors (the enrichment level of the final core is lower than that of the feed due to the conversion ratio being <1).
Having a two fluid reactor introduces all sorts of other horrible problems which explain why such developments were abandoned in favour of single fluid designs.

Go back & reread the article including the footnotes - I am proposing a two fluid reactor. I've assumed an at least 80% enriched 235U start up fuel because that's at the lower end of "bomb grade" HEU (Hiroshima's "little boy" bomb was enriched to 80%) & the USA already makes/uses lots of it in Naval reactors.

LWR or HWR can produce plutonium which can be used for breeders. All the breeder programs undertaken so far have used this route. MSFR is, if anything, more neutron efficient than the fast solid fuel reactors and are quite useful if reprocessing is not given up.Russia, India and. China are developing their programs this way only. Of course enriched uranium fuelled programs are also feasible if followed by reprocessing.

I've put together a paper for an ASME journal which encourages its readers to work out some of the "engineering details" that must be to dealt with before a "real" MOSEL or MSFR could be built. ( that draft is ATTACHED to the last comment made to the topic that I started about MOSEL )

I encourage you to get started on it now.

If anyone can answer (definitively) any of the questions it poses, please post your answer(s) there. Questions are welcomed too.